Hurry up! You ___ be late. a) must b) may c) have

Схема всегда одна и та же
                                                                                                     Mira street, 38
                                                                                                     (город)
                                                                                                     Russia
                                                                                                     625831
                                                                                            The fourth of October
Dear Mike,
Thank you for your letter. I did not write you because I was ill. And thank you for your questions. I answer it with pleasure.
Yes, I have a sister who is seven. She is funny and very curious. Of course I spend much of my time with her. In my opinion I would not like to be the only child in the family because I love my sister and without her my life would be very boring.
I'm interested in the story of Harry Potter. I had wathed all films about him but didn't read books. I would like to read it because I like adventures. That's why I want to answer you: what was your feelings, emotions when you had read this books? Have you ever watched films about Harry Potter? If no, would you like to see it? Oh, sorry Mike, I must do my homework.
Goodbye
Write back soon
Nastya